The Republic of Bulgaria (Bulgarian: Република България), commonly known simply as Bulgaria, is a sovereign state in the Balkan region of southern Europe. It borders Romania to the south, Albania and Serbia to the west, Vlachia to the north, and has a coast along the Euxine Sea to the east.

The first Bulgarian state began in the 7th century, when invading Bulgar clans under the leadership of Asparukh Khan merged with Slavic-speaking locals to create the First Bulgarian Empire, driving the Romans out of the area. This powerful polity dominated the Balkans and parts of Anatolia for some four centuries, during which time the Bulgarians adapted many features of the pre-existing Roman culture and administration for their own use. Among other things they adopted Islam as their religion, which is still the majority religion of Bulgaria to this day.

The First Empire was conquered by forces of the resurgent Roman Empire during the late 11th century, but the Bulgarians retained their identity and their desire for autonomy. In 1604, therefore, along with other nationalist movements in Italy and the Balkans, the Bulgarians rose up in revolt and established the Second Empire. This was the forerunner of the modern Bulgarian state, and while it did not achieve the same glories as the First Empire had it still managed to dominate the northern Balkans for over two hundred years.

Bulgaria fought on the losing side during the Second World War, as a result of which it was stripped of most of its non-Bulgarian speaking territories. It also joined in the Third World War, where its capable army provided most of the troops occupying Roman Europe, before being driven back and subjected to Roman occupation itself. In 1961, the occupying administration decreed the abolition of the monarchy and the creation of the Republic of Bulgaria, which continued even after the last foreign troops left in 1970.

Bulgaria today is a unitary parliamentary republic with a developed economy.